Disorders of consciousness range from deep coma in a patient with a mass lesion to delirium in a hospitalized elderly patient. Neurohospitalists are often asked to determine the etiology of the patient's altered state and to provide prognostic information and treatment recommendations. This review addresses the common syndromes associated with consciousness disorders, including coma, vegetative and minimally conscious states and syncope. A comatose patient, by definition, has eyes closed with no response to voice or pain and no comprehensible speech or awareness of self and surroundings. Patients typically evolve into a chronic disorder of consciousness, often initially a vegetative state and then potentially into a minimally conscious state. Syncope is a rapid-onset and self-limited loss of consciousness which is typically accompanied by loss of postural tone. Transient global amnesia (TGA) is a clinically defined condition with abrupt onset of anterograde and variable retrograde amnesia lasting up to 24 hours.